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Tetraphase Claws Back From Failed Study, Eyes FDA Filing With New Data

New data have given new life to Tetraphase Pharmaceuticals (NASDAQ: TTPH), which now has a shot to bring an experimental antibiotic to market despite a failed trial in the past.

The Watertown, MA, company reported positive results late Tuesday in a 500-patient Phase 3 study of its lead antibiotic, eravacycline, in patients with complicated intra-abdominal infections (cIAI). The drug, administered intravenously, met its goal of performing comparably to—not necessarily better than—the antibiotic meropenem at wiping out the infections in these patients a few weeks after the first dose of Tetraphase’s drug. There were no serious side effects from treatment; the most common problems tied to Tetraphase’s drug were nausea, vomiting, and infusion site reactions, but those side effects occurred in less than 5 percent of patients.

The company provided only top-line results from the study. More details will come at a future medical meeting. Shares surged more than 30 percent pre-market before settling into a roughly 11 percent gain as of 10:01 a.m. ET.

The news has emboldened Tetraphase to seek approval of eravacycline despite mixed results in its Phase 3 program—two trials have now succeeded, one has failed, and the other is ongoing. Eravacycline is the only experimental Tetraphase drug remotely close to market. With the new data in hand, Tetraphase will apply for approval in Europe in the third quarter of this year and in the U.S. in early 2018.

Tetraphase’s eravacycline is a broad-spectrum antibiotic, meaning it is being developed to handle multiple types of bacterial infections. New antibiotics are sorely needed due to the rise of deadly drug-resistant bugs. According to the Centers for Disease Control and Prevention, 2 million Americans each year suffer from drug-resistant bacterial infections, and more than 23,000 of them die. Tetraphase and another Boston-area company, Paratek Pharmaceuticals (NASDAQ: PRTK), both have a chance to bring new weapons to the fight in the near-term. Paratek aims to file for approval of a broad-spectrum antibiotic, omadacycline, next year.

Now Tetraphase’s antibiotic may be in the mix as well. Despite the availability of other options for cIAI, some of which are generic and cheap, Tetraphase is hoping that eravacycline’s “unique spectrum of coverage” will make it a key addition in hospitals dealing with these infections, chief commercial officer Larry Edwards said on a conference call Tuesday afternoon. “We think that it has a good opportunity if priced appropriately,” he said.

The company went public in 2013 at $7 per share and climbed to as high as $47.55 in July 2015 months after the first of its Phase 3 trials, a successful study of eravacycline, administered intravenously, in patients with cIAI. The drug was comparable to the antibiotic ertapenem, which is used to battle bacteria that can lead to infections after certain surgeries. Tetraphase had originally planned to use data from that trial (Ignite1), and a second study(Ignite2) in patients with complicated urinary tract infections (cUTI)—in which patients transitioned from an IV form of eravacycline to an oral dose—to support FDA approval.

Yet nearly 80 percent of Tetraphase’s value was wiped out when Ignite2 failed in September 2015. Shares have traded around or below its IPO price ever since, but the company still had a chance to bounce back. Following discussions with the FDA, it designed and ran another Phase 3 trial, named Ignite4 that, like Ignite1, tested the antibiotic in IV form in patients with cIAI. According to regulatory filings, the FDA advised Tetraphase that positive results from that study, combined with its previous successful trial, could be enough to support approval for IV eravacycline.

Tetraphase has embarked on that plan while waiting for a separate study to wrap up, Ignite3, which tests only the IV form this time in cUTI patients. Enrollment in that study should conclude later this year. It hasn’t said when to expect results; if Tetraphase succeeds, it would seek approval of eravacycline in cUTI patients as well.

“We believe that eravacycline has the potential to play a key role in the treatment of serious hospital infections, and we are another step closer to realizing that goal,” said president and CEO Guy Macdonald, in a statement.

Ben Fidler is Xconomy's Deputy Editor, Biotechnology. You can e-mail him at bfidler@xconomy.com Follow @benthefidler